Thomas mccoujbray



(No Model.)

, T, MQOOUBRAY.

*TELEPHONIG OR ANALOGOUS ELECTRODE.

No. 533,729. Patented Feb. 5,1895.

I 1 Ill/6711237:-

w GW 0 UNITED STATES THOMAS MOCOUBRAY, OF NEIV YORK, N. Y,

TELEPHONIC OR ANALOGOUS ELECTRODE.

SPECIFICATION formin part of Letters Patent No. 533,729, dated February5, 1895.

Application filed August 9, 1894- Serial No. 519,911- (No model.)

To all whom it may concern.-

Be it known that I, THOMAS MOOOUBRAY, a citizen of the United States,residing at New York, in the county of New York and State of NewYork,have made a new and useful In vention in Telephonic or AnalogousElec trodes, of Which'the following is a specification.

My invention is directed particularly to improvements in that type oftelephonic electrodes known in the art as Hunnings transmitters in whichthe transmitter is composed of a mass of comminuted particles ofconducting material, usually powdered carbon orthe like, and its objectsare, first, to devise an electrode of this type which shall be free fromthe objectionable feature of packing or assuming a solid nature when inuse; second, to devise an electrode of the type indicated which shallhave increased conducting qualities and be free from the absorption ofmoisture, thus rendering the apparatus more efficient in thetransmission of articulate speech, musical tones, and other sounds.

For purposes of illustration, I have shown in the accompanying drawing,as one instance of its employmentin practice, the position occupied bythe electrode material claimed herein, in a telephone transmitter of thecom struction shown and described in Letters Patent No. 527,214, grantedto me October 9,1894.

I have discovered that a residuum from petroleum, from petroleum tarwhich is taken from the stills in irregular shaped lumps, and usually ofa honey-combed form is capable of producing, when prepared, ashereinafter described, an electrode for telephonic apparatus of greatefficiency. I take this residuum of petroleum or petroleum tar in itscrude form as it is taken from the stills andcrush it or reduce it to agranular form. I then pass it through a sieve of say forty (40) meshesper square inch for the purpose of removing the outlet pipe, and Ipartially fill this retort with the granulated powder as prepared. Ithen cover the powder with plumbago so as to exclude the air and placethe retort in a bed of live coals to a point near the top of the vessel,bringing it preferably to a red or almost white heat. The material asthus heated gives off a gas which ignites at the mouth of the outletpipe and continues to burn until the volatile matter has been all drivenoff. In this manner I ascertain, when the material has reachedapproximately the proper point of carbonization. This gives me a powderof fairly uniform grain and of about the hard ness of glass with welldefined edges. The material is then removed from the retort and is readyfor use and is placed in telephonic transmitters in a manner wellunderstood by those skilled in the art.

I do not limit myself to the above method of carbonization of theresiduum of petroleum distillation, as it might be carbonized, ifpreferred, in the form in which it comes from the stills but a greaterheat and a longer time would be required to effect such carbonization,or to drive off the volatile gases, and my claims include such method;nor do I limit myself to the above described treatment of a residuum ofpetroleum, such as petroleum tar, so as to make it a conductor ofelectricity particularly adapted for use in the telephonic art, as Ibelieve it is broadly new with me, in the art of telephony, to utilizesuch a residuum when properly treated so as to make it a condoctor ofelectricity; nor do I limit myself to any special manner of utilizingthe powder as thus prepared, as it obviously might be utilized intelephonic receivers or in any manner in which analogous powders areused in the art of telephony,

Having thus described my invention, what I claim, and desire to secureby Letters Pat ent of the United States, is-

1. The described method of preparing a carbon powder from the residuumof petroleum distillation, consisting in crushing or grinding saidmaterial into a powder-like form and then subjecting the powder tocarbonization.

2. The described method of preparing a carbon powder from the residuumof petroleum distillation, consisting in crushing or grindin g saidmaterial into a powder-like form, and

then sizing the powder and finally carbonizing it.

3. The described method of preparing a carbon powder from the residuumof petroleum distillation, consisting in crushing or grinding saidmaterial into a powder-like form, then passing the powder through asieve of given mesh and again separating the finer particles from thecoarser, and finally carbonizing the particles retained in the secondsieve.

4. A telephonic electrode made from a residuum of an oil, such aspetroleum, which residuum has been previously treated so as to make it aconductor of electricity.

5. A telephonic electrode consisting of comminuted particles of a carbonresiduum of an oil, such as petroleum, which residuum has an oil such aspetroleum, which particles are 25 re-carbon ized.

In testimony whereof I have hereunto subscribed my name this 6th day ofAugust, 189i.

THOMAS MOCO'U'BRAY. Witnesses:

(J. J. KINTNER, BL M. ROBINSON.

